Tint inspection is a method of nondestructive testing. It is a surface
inspection method, mainly used to detect surface damage such as cracks that
cannot be recognized by the naked eye, such as the detection of stainless steel
near surface defects (cracks), pores, porosity, stratification, penetration and
fusion defects (also known as PT inspection). It IS SUITABLE FOR INSPECTING
COMPACT METAL MATERIALS (WELDS), NON-METALLIC MATERIALS (glass, ceramics,
fluorine plastics) and defects (cracks, pores, etc.) on the surface of
products.
The basic principle of color detection: the surface of the material is
coated with colorant, and the colorant penetrates the damaged part. Rinse the
colorant off the surface after a period of time. The surface that has been
cleaned is coated with a developer, and the damaged area can be seen clearly
because the colorant has penetrated into it. The capillary phenomenon is mainly
used to make the permeate into the defect, and the surface permeate is removed
by cleaning agent, and the permeate remains in the defect, and the capillary
action of imaging agent is used to adsorb the residual permeate in the defect to
achieve the purpose of testing the defect.
Pre-clean the workpiece surface
Before applying penetrant inspection surface, should use cleaner clean
surface clean, makes checked surface without oil, rust, chip, and other dirt
lacquer layer (such as inspection of weld, on the surface of weld and weld edge
should not be oxided surface scale, welding slag, spatter, etc), and then, makes
the surface of the workpiece tested to fully dry.
Dye penetrant
After evenly spraying the surface of the treated and clean workpiece with
osmotic agent, permeate it for 5-15 minutes.
Cleaning and drying
After 5-15 minutes of penetration, and before applying the imaging
agent:
(1) Use a cleaning agent to clean the permeant sprayed on the surface of
the workpiece, so that the inspected surface should be clean;
(2) Wipe dry with clean gauze or dry naturally at room temperature Note:
when removing excess penetrant, over-cleaning or insufficient cleaning should be
prevented (ensure that there is no penetrant on the surface of the
workpiece).
imaging
After fully shaking the developing agent, spray evenly on the surface of
the inspected workpiece (cleaned and dried workpiece) at a distance of
150mm-300mm, spraying Angle is 30° -40 °, and the developing time is not less
than 7 minutes.
To observe the
1, the observation of the trace, should be applied after the development
agent, until the size of the trace does not change, about 7-15 minutes, the
observation of the development should be in the application of the development
agent within 7 to 60 minutes.
2, observe the trace, must be in sufficient natural light or white
light.
3, the observation shows the trace, can be used by naked eye or 5- 10 times
magnifying glass.
4, can not distinguish the true and false defect traces, should be the part
of the second test.
Results judgment and recording
1, according to the size of the trace and color to judge the size and
severity of the defect.
2. If the ratio of the length and width of the defect display trace is not
less than 3, it is called the linear defect trace, and the strip defect will
show the linear trace.
3. If the ratio of the length and width of the defect trace is less than 3,
it is called circular defect trace. Nearly circular defects such as pores, for
example, will show a circular trace.
4, defect display trace, according to the need to record with photography,
schematic diagram or peeling agent, etc.
5. Mark the parts where the defects on the inspected surface show
traces.
The inspection report includes:
1. Code name, name, material, surface state and quantity of the inspected
workpiece;
2, the entrusting unit, according to the technical documents and inspection
requirements;
3. Model and category of tinted flaw detection agent;
4, detection sensitivity (indicate the type of test block), flaw detection
results;
5. Signature of flaw detection personnel and audit personnel;
6. Application date and report date.
